Self-energizing retractable powered drive roller assembly

ABSTRACT

A drive roller assembly for propelling loads, in which a power driven roller or a plurality of rollers coupled universally in series are mounted independently at each end of a roller, each mounting including a cam to elevate the adjacent end of a roller, and each cam being operated by slip type clutch rings encircling a drum, the rings being continuously rotated by the same power source which drives the rollers, and yieldably transmitting power through the drum to rotate a cam with sufficient force to press a roller into driving traction with a load, at the same time automatically adjusting the attitude of the plane of the roller to generally match the plane of the bottom of the load engaged.

United States Patent Macpherson 51 Sept. 12, 1972 [72] Inventor: Duncan ll. Macpherson, Edmonds,

Wash.

[73] Assignee: Western Gear Corporation, Lynwood, Calif.

22 Filedz Oct.9,1970

21 Appl.No.: 79,554

Casel ..198/l27 FOREIGN PATENTS OR APPLICATIONS 1,050,270 2/1959 Germany l 98/1 27 Primary Examiner-Richard E. Aegerter Assistant Examiner-Douglas D. Watts Attorney-Huebner & Worrel [57] ABSTRACT A drive roller assembly for propelling loads, in which a power driven roller or a plurality of rollers coupled universally in series are mounted independently at each end of a roller, each mounting including a cam to elevate the adjacent end of a roller, and each cam being operated by slip type clutch rings encircling a drum, the rings being continuously rotated by the same power source which drives the rollers, and yieldably transmitting power through the drum to rotate a cam with sufficient force to press a roller into driving traction with a load, at the same time automatically adjusting the attitude of the plane of the roller to generally match the plane of the bottom of the load engaged.

16 Claims, 1 1 Drawing Figures SELF-ENERGIZING RETRACTABLE POWERED DRIVE ROLLER ASSEMBLY BACKGROUND OF THE INVENTION Modern aircraft transportation involves movement of heavy modules or containers from loaders or portable docks into or out of aircraft. The modules include food kitchens or housings containing other supplies or equipment; the containers-also may be for baggage or other items being shipped.

It is known in this connection to provide the decks of aircraft and of both stationary docks and portable ones, the latter sometimes termed loaders, with inverted casters, balls, rollers or airlifts to movably support the modules or containers, generally hereinafter mentioned as loads. 1

For power movement of the loads over the supporting means, power driven wheels or rollers have been employed in friction drivingengagement with the bottom or sides of the load.

Various means have been utilized to hold the wheels or rollers in traction engagement with the'load and to retract the wheels or rollers when the movement has been completed or when shifting the travel direction of the load, or in the event of power failure. In the-latter situation, if the wheel or roller should remain in frictional engagement with a load, it will act as a brake or drag and hinder manual movement or propulsion by auxiliary apparatus.

The wheels or roller assemblies, especially if located in the aircraft, need to be compact in order to conserve space and to fit in the area allotted for the purpose. In case of very heavy loads, sometimes it is desirable to provide more driving surface than a single roller of conventional length (8 inches 12 inches more or less) will furnish. That problem is not best solved by duplicating the units each with a motor and reduction gearing, or by the expedient of extending the length of theroller. The duplication adds undesirable weight and consumes additional space. A single long roller has the disadvantage of an inability to properly contact the load if there is a transverse irregularity in the bottom or wall of the load to be engaged. In other words, an angular open space may develop between the bottom of the load and the driving surface of the roller. This deficiency is especially pronounced when both ends of the roller rise and fall in the same plane by reason of identical manipulation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power driven roller system which may embody a series of rollers in generally axial alignment but which are mounted independently at each end and are able to assume different attitudes, and even operate in different horizontal planes.

This is accomplished, using a single motor and reduction gear, through employment of universal or flexible joints, and novel roller mounts. Each roller mount includes a bearing structure for a stub shaft extending from each end of the roller. The shaft is rotated at a constant speed by the motor through the reduction gear. Coupled with the constant speed drive at each connection with a roller stub shaft is a ring type slip clutch which co-acts with a cam to elevate the immediately adjacent end of the roller until it comes into driving engagement with a load. The action is independent at each end of each roller. When the power is shut off, the roller descends under the influence of a spring out of engagement with the load.

The assembly includes a supporting frame work in the form of a channel 20. A motor'and gear reduction unit21 is mounted at one end of the channel. An electrical conduit 22 is carried through the channel from the motor end to a plug 23 at the opposite end.

Intermediate thetwo ends a plurality (twobeing illustrated) of roller assemblies 24 and 25 are supported, and provided with independent mounts and controls enabling individual end elevation to accommodate uneven levels on the bottom of a load being propelled.-

.Universal joint assemblies 26 and 27 afford drive coupling between the gear unit and the nearest adjacent roller assembly, and between the latter assembly and the next roller assembly in line.

Each drive roller'assembly includes in the'mount and control a slip clutch drive mechanism 30 which takes power from the roller drive and through a cam 32 elevates the roller into load'engagement. This action is opposed by a spring 34 which returns the roller to Iowered'non-engagement when the power is off.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary top plan view of a conveyor assembly with the self-energizing retractable powered drive roller assembly installed. I

FIG. 2 is a section, somewhat enlarged, taken on line 2-2 of FIG. 1.

FIG. 3a is a top plan view of the left-hand portion of the assembly of FIG. 1; and FIG. 3b is a continuation of I FIG. 3a.

FIG. 4 is a section, enlarged, taken on line 4-4 of FIG. 3a.

FIG. 5 is a section taken on line 5-5 of FIG. 4.

FIG. 6 is a further enlarged section of mechanism shown in the right hand area of FIG. 5.

FIG. 7 is a section taken on line 7--7 of FIG. 6.

FIG. 8 is a section taken on line 8-8 of FIG. 6.

FIG. 9 is a section taken on line 9--9 of FIG. 6. In this view, the roller is lowered.

FIG. 10 is a view similar to FIG. 9 showing the roller elevated.

PREFERRED EMBODIMENT OF THE INVENTION For environmental purposes, FIG. 1 illustrates the decking D of a cargo hatch H of an aircraft, contiguous to which is a portable loader L.

Mounted in the decking are parallel trains of idle rollers R, and such rollers have counterparts in the form of similar idle rollers LR in the portable loader.

The self-energizing retractable power roller assembly PRA embodying the present invention is mounted in the aircraft decking close to the outer edge thereof. If necessary or desirable, a similar roller assembly may be mounted on theportable loader.

In FIG. 2 there is shown in phantom fraction a load in the form of a kitchen module KM being shifted from the loader into the aircraft.

The framework channel 20 contains three support boxes 20a, 20b and 20c. The boxes are for reinforcement and to provide mountings for operating parts as will develop.

- wardly from its pivot,

The support box 20a has the motor and reduction gear unit 21 bolted to it at one end, and supports the,

universal joint assembly 26 and adjacent associated operating parts. The box 20b supports the universal joint assembly 27 and its adjacent associated operating parts; and the box 200 supports the operating parts at the end most remote from the motor, and also the electrical plug 23 which is the terminal for the conduit 22.

Roller assembly 24 extends between boxes 20a and 20b, and roller assembly 25 extends between boxes 20b and 20c.

Referring to FIGS. 4 and 5, the reduction gear unit delivers power through a shaft 26 to the universal joint unit 26. Two universal joints are illustrated at 26a and 26b with a common center shaft 37.'The dual joints are desirable in order to accommodate relative axial displacement between the gear shaft and a stub shaft 38 of the roller assembly 24. Other forms of flexible couplings may be employed if desired.

The end of the universal joint opposite the shaft 36 is keyed or pinned at 41 ,to the stub shaft 38 which is journalled in a manner later described. The stub shaft 38 is enlarged into or rigidly secured to an annular plug 45. The latter is fixed in the end of a power roller shell 46 which is surfaced by a suitable friction sleeve 47, neoprene, for example, completing the roller 48. Thus, the roller is given a direct constant velocity drive from the shaft 36,'through the universal joint assembly 26, and the stub shaft 38. This prevails irrespective of the elevational position of the roller.

The universal joint assembly 27, in the box 20b, carries the direct drive from the first roller 48 in the series, to the next roller 50 of the assembly 25.

The rollers individually may be raised or lowered for engagement with or disengagement from a load. Moreover, the raising or lowering of each roller may vary at each end thereof, so that if the bottom of a load be transversely inclined, each roller will adapt its attitude accordingly.

To accomplish such purpose, the pertinent mechanism will be described next, using as an example the operative parts adjacent the universal joint assembly 26.

The box 20a is formed with an end wall 55 designed with a relief cut-out 56. (See FIG. 9.) The cut-out is to afford clearance for the stub shaft 38.

The end wall 55 supports one end of a pin 60. The pin is further supported by bracket members 61 and 62 mounted in the channel 20.

This pin 60 serves two functions. The first is to provide a pivotal mounting for one end of a radial arm 64, and the second is to carry the coil spring 34. The spring includes a horizontal terminus 66 parallel to the spring axis. This terminus seats in a groove 78 in the upper edgesurface of the arm 64, the opposite end 80 of the spring bearing against a stop 81. The spring thus biases the radial arm 64 downwardly from its pivot 60.

The radial arm carries the stub shaft 38 through the agency of bearing 84. Thus, when the arm is swung upby a force overcoming the spring bias, the stub shaft 38 is raised, and carries with it the adjacent end of the roller 48. The radial arm is swung upwardly by a take-off from the power delivered through the shaft 36. The take-off includes the ring type slip clutch 30 and cam mechanism 32.

The latter mechanism involves a clutch drum 88, and a thrust element illustrated in the form of a cam 89 conveniently formed as an integral unit. The unit is mounted for rotation on the stub shaft 38 by a bearing 90. Rotation is imparted to the clutch drum 88 by a key 92 projecting from the plug 45 over the periphery of the drum 88, the projecting portion of the key impinging against the ends 94 of slip rings 95. These rings are in the nature of C rings, circular but interrupted to freely accommodate the key 92, and present the ends for abutment. They possess spring characteristics and are designed resiliently to hug the barrel with sufficient tenacity to transmit driving force of the key to the drum, but to slip upon encountering a predetermined resistance. The interruption of the rings should be of sufiicientmagnitude to afford lost motion or limit free wheeling when the power is off and the springs are in effect to retract the rollers.

The cam 89 is of single lobe type with a relief 93 diametrically opposite the peak 96. It cooperates with an idle roller 97, riding on the same when rotating from the at rest position of FIG. 9 to the elevated working position of FIG. 10.

The elevating movement of the cam will cease when a predetermined resistance thereto is presented by the roller pressing against a load. Provision, however, is made to limit elevation of the roller when no load is imposed upon it.

- When the motor is running and a load is in traction contact with the rollers, the load itself controls the maximum elevation of the rollers, and the slip clutch action of the rings 95 on the drum 88 will cause the rollers to fluctuate up or down to the extent necessary in order to maintain the rollers in frictional driving contact with the load.

If the motor is started before the load is over the rollers, or continues to run after the load has passed, stop link devices come into play, to limit the height to which the disengaged rollers rise.

Each of these devices comprises a link in the form of an elongated closed loop pivotally anchored on the same pin 101 which mounts the cam support roller 97. The pin 101 is supported in a base 102 which may be a part of, or an adjunct to, the box 200.

The stop link embodies parallel sides 103 and 104 which slidablyembrace a needle bearing 105 on the stub shaft 38. Thus, as the shaft may rise or fall under operating conditions, the link will rock to follow it; and when the shaft becomes elevated to the maximum predetermined height, the needle bearing reaches the upper end of the loop and further elevation is thus inhibited. Under this condition, the slip rings ride around the slip clutch drum in the same manner as they do when a load is pressing on the rollers.

An annular housing encloses the slip rings. A protective cover 111 shields the general assembly of operating parts located between the universal joint assembly and the adjacent end of the roller.

The operating mechanism described as interposed between the motor 21 and the roller 48 is substantially duplicated in conjunction with the box 20b between the adjacent ends of the rollers 48 and 50; instead of coupling of the universal joint mechanism with the motor gear shaft 36, the power input is delivered to the universal joint assembly 27 by a roller stub shaft 114 is at the end remote from the stub shaft 38. The stub shaft 114 is mounted and controlled by an arm, cam

mechanism, slip clutch, stop link and spring similar to those previously described. The universal joint assembly 27 connects with a stub shaft 115 of the roller assembly 25, which stub shaft 115 is also mounted and controlled in the same manner as stub shaft 114.

At the end of roller 50 opposite the stub shaft 115 is a stub shaft 116, associated with mounts and controls of the same character as utilized in conjunction with the other stubshafts.

The system will operate with the motor running in either direction, to propel a load in either direction.

When the motor is running, a direct, constant speed power drive is communicated to both rollers, or additional ones, if added to the series. The stub shaft at each end of each roller could be merely extensions of a through shaft, if preferred. The operation would be the same. In either case, the output is transmitted at each end of each roller independently to operate the slip clutches, and thus independently move the respective ends of each roller into a proper elevation and attitude to accomplish maximum traction contact of the rollers with a load. The mounts for the stub shafts should be designed with sufficient tolerances to afford such action. 1

When the motor is shut off, or power fails, the rollers become idle, and the springs augmented by the weight of the roller assemblies will return the rollers to retracted positions. In this function, the clutches are free of resistance to the extent of circumferential spacing of the ends of the rings. The spring action can be supplemented, if desired or necessary, by a momentary reversal of the motor which will initially retract the rollers. Of course, after the cams have passed the at rest position shown in FIG. 9, continued power would raise the rollers while rotating them in the opposite direction.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention.

What I claim is:

1. A drive roller assembly for propelling a load by rolling traction of a roller with a load comprising: a roller, means mounting the roller whereby it may be moved from a retracted position to an advanced position in driving engagement with a load, power means fixedly mounted, coupling means connecting the power means with the roller to rotate the latter, a slip clutch interposed between the coupling means and the means mounting the roller transmitting power to the latter to advance the roller to driving engagement position, the slip clutch comprising a drum, a slip type interrupted ring frictionally embracing the drum, and a power driven key engaging an end of the ring to rotate the same, the mounting means comprising a shaft extending from the roller, an arm pivotally mounted on a fixed base and swingably supporting the shaft, a cam encircling the shaft, the cam being connected with the clutch drum to be rotated by the latter, and a cam roller mounted on a stationary pivot, the cam being engageable with the cam roller.

2. A drive roller assembly as defined in claim 1, in which the cam and the clutch drum are integral.

3. A drive roller assembly as defined in claim 1, which includes a stop link surrounding the shaft to limit advance of the roller.

4. A drive roller assembly for propelling a load by rolling traction of a roller with a load comprising: a roller, means including a thrust element mounting the roller whereby it may be moved from a retracted nondriving position to an advanced positionin driving engagement with a load, power means coupling means connecting the power means with the roller to rotate the latter, and a slip clutch interconnecting the coupling means and the thrust element transmitting power to the latter to actuate the thrust element and thereby advance the roller to driving engagement position.

5. A drive roller assembly as defined in claim 4, in which the coupling means includes a flexible joint whereby the roller may be shifted from a retracted to an advanced position while being rotated by the power means.

6. A drive roller assembly as defined in claim '5, in which the means mounting theroller comprise an independent unit at each end of the roller,'the coupling means connects the power means and roller at one end of the latter, one slipclutch is interposed between such coupling means and the mounting unit at said one end, and a second slip clutch is interposed between the opposite end of the roller and the'mounting unit at said opposite end. 1

7. A drive roller assemblyas def'med in claim 6, in which a second roller is disposed in general axial alignment with thefirstroller identified,'third and fourth mounting units similar to those mounting the first roller support the second roller at its respective ends, third and fourth slip clutches are interposed between such ends and the third and fourth mounting units respectively, and a flexible joint connects-the first roller to the second roller for rotating the latter.

8. A drive roller assembly as defined in claim 7, in which the flexible joint comprises two spaced universal joints interconnected by a shaft.

9. A drive rollerv assembly as defined in claim 4, in which each slip clutch comprises a drum, a slip type interrupted ring frictionally embraces the-drum, and a power driven key engages an end of the ring to rotate the same.

10. A drive roller assembly for propelling a load over a base comprising: a motor, a-traction roller, a fixed speed coupling interconnecting the motor and traction roller, means including a thrust element mounting the traction roller for shiftable movement between a retracted position and an advanced load engaging position, a second coupling including a slip .clutch interconnecting the fixed speed coupling and the thrust element to actuate the latter for advancing the traction roller, said second coupling including a clutch drum,-an interrupted ring frictionally embracing the drum and presenting spatially separated end surfaces, and a rotatable member driven by the fixed speed coupling adapted to engage one or the other of the end surfaces.

1 l. A drive roller assembly for propelling a'load over a supporting medium comprising: a frameelement including a-base, a motor fixedly mounted on the frame element, a traction roller embodying afirst axial shaft extension at one end of the roller, a second shaft extension at the opposite end of the roller, a first cam means encircling the first shaft extension, a secondcam means encircling the second shaft extension, each cam means being independently operable to advance the adjacent end of the roller outwardly from the base into a load engaging position, a flexible drive coupling between the motor and the first shaft extension, slip clutch means between the first shaft extension and the first cam means to yieldably transmit rotation of such shaft extension to the first cam means, and slip clutch means between the second shaft extension and the second cam means to yieldably transmit rotation of the latter shaft extension to the second cam means.

12. A drive roller assembly as defined in claim 11, in which the flexible drive coupling comprises spaced universal joints interconnected by a shaft.

13. A drive roller assembly as defined in claim 11, in which a first arm is pivotally mounted on the base and embraces the first shaft extension, and a second arm is pivotally mounted on the base and embraces the second shaft extension, the arms serving independently to confine the shaft extensions and thereby the roller to predetermined orbital movements from retracted positions to positions outwardly of the base, the roller in retracted position being out of engagement with a load and in advanced position being disposed for traction engagement with a load.

14. A drive roller assembly as defined in claim 11, in which stop links are pivotally mounted on the base, one stop link encircling the first shaft extension, and another stop link encircling the second shaft extension, the stop links serving to limit the advance of the roller.

15. A drive roller assembly as defined in claim 14, in which springs carried on the base independently bias each arm to a retracted position when the motor is not operating, the bias being overcome when the motor is operating.

16. A drive roller assembly as defined in claim 10 in which a second roller is generally axially aligned with and spaced from the first roller, the second roller embodies shaft extensions similar to the first one defined, cam means and slip clutch means similar to those defined in claim 10 are associated with the shaft extensions of the second roller, and a flexible coupling connects adjacent shaft extensions of the rollers. 

1. A drive roller assembly for propelling a load by rolling traction of a roller with a load comprising: a roller, means mounting the roller whereby it may be moved from a retracted position to an advanced position in driving engagement with a load, power means fixedly mounted, coupling means connecting the power means with the roller to rotate the latter, a slip clutch interposed between the coupling means and the means mounting the roller transmitting power to the latter to advance the roller to driving engagement position, the slip clutch comprising a drum, a slip type interrupted ring frictionally embracing the drum, and a power driven key engaging an end of the ring to rotate the same, the mounting means comprising a shaft extending from the roller, an arm pivotally mounted on a fixed base and swingably supporting the shaft, a cam encircling the shaft, the cam being connected with the clutch drum to be rotated by the latter, and a cam roller mounted on a stationary pivot, the cam being engageable with the cam roller.
 2. A drive roller assembly as defined in claim 1, in which the cam and the clutch drum are integral.
 3. A drive roller assembly as defined in claim 1, which includes a stop link surrounding the shaft to limit advance of the roller.
 4. A drive roller assembly for propelling a load by rolling traction of a roller with a load comprising: a roller, means including a thrust element mounting the roller whereby it may be moved from a retracted non-driving position to an advanced position in driving engagement with a load, power means coupling means connecting the power means with the roller to rotate the latter, and a slip clutch interconnecting the coupling means and the thrust element transmitting power to the latter to actuate the thrust element and thereby advance the roller to driving engagement position.
 5. A drive roller assembly as defined in claim 4, in which the coupling means includes a flexible joint whereby the roller may be shifted from a retracted to an advanced position while being rotated by the power means.
 6. A drive roller assembly as defined in claim 5, in which the means mounting the roller comprise an independent unit at each end of the roller, the coupling means connects the power means and roller at one end of the latter, one slip clutch is interposed between such coupling means and the mounting unit at said one end, and a second slip clutch is interposed between the opposite end of the roller and the mounting unit at said opposite end.
 7. A drive roller assembly as defined in claim 6, in which a second roller is disposed in general axial alignment with the first roller identified, third and fourth mounting units similar to those mounting the first roller support the second roller at its respective ends, third and fourth slip clutches are interposed between such ends and the third and fourth mounting units respectively, and a flexible joint connects the first roller to the second roller for rotating the latter.
 8. A drive roller assembly as defined in claim 7, in which the flexible joint comprises two spaced universal joints interconnected by a shaft.
 9. A drive roller assembly as defined in claim 4, in which each slip clutch comprises a drum, a slip type interrupted ring frictionally embraces the drum, and a power driven key engages an end of the ring to rotate the same.
 10. A drive roller assembly for propelling a load over a base comprising: a motor, a traction roller, a fixed speed coupling interconnecting the motor and traction roller, means including a thrust element mounting the traction roller for shiftable movement between a retracted position and an advanced load engaging position, a second coupling including a slip clutch interconnecting the fixed speed coupling and the thrust element to actuate the latter for advancing the traction roller, said second coupling including a clutch drum, an interrupted ring frictionally embracing the drum and presenting spatially separated end surfaces, and a rotatable member driven by the fixed speed coupling adapted to engage one or the other of the end surfaces.
 11. A drive roller assembly for propelling a load over a supporting medium comprising: a frame element including a base, a motor fixedly mounted on the frame element, a traction roller embodying a first axial shaft extension at one end of the roller, a second shaft extension at the opposite end of the roller, a first cam means encircling the first shaft extension, a second cam means encircling the second shaft extension, each cam means being independently operable to advance the adjacent end of the roller outwardly from the base into a load engaging position, a flexible drive coupling between the motor and the first shaft extension, slip clutch means between the first shaft extension and the first cam means to yieldably transmit rotation of such shaft extension to the first cam means, and slip clutch means between the second shaft extension and the second cam means to yieldably transmit rotation of the latter shaft extension to the second cam means.
 12. A drive roller assembly as defined in claim 11, in which the flexible drive coupling comprises spaced universal joints interconnected by a shaft.
 13. A drive roller assembly as defined in claim 11, in which a first arm is pivotally mounted on the base and embraces the first shaft extension, and a second arm is pivotally mounted on the base and embraces the second shaft extension, the arms serving independently to confine the shaft extensions and thereby the roller to predetermined orbital movements from retracted positions to positions outwardly of the base, the roller in retracted position being out of engagement with a load and in advanced position being disposed for traction engagement with a load.
 14. A drive roller assembly as defined in claim 11, in which stop links are pivotally mounted on the base, one stop link encircling the first shaft extension, and another stop link encircling the second shaft extension, the stop links serving to limit the advance of the roller.
 15. A drive roller assembly as defined in claim 14, in which springs carried on the base independently bias each arm to a retracted position when the motor is not operating, the bias being overcome when the motor is operating.
 16. A drive roller assembly as defined in claim 10 in which a second roller is generally axially aligned with and spaced from the first roller, the second roller embodies shaft extensions similar to the first one defined, cam means and slip clutch means similar to those defined in claim 10 are associated with the shaft extensions of the second roller, and a flexible coupling connects adjacent shaft extensions of the rollers. 